Lists

Introduction to Python for Developers

George Boorman

Curriculum Manager, DataCamp

Problem

# Variables of product prices
price_one = 10
price_two = 20
price_three = 30
price_four = 15
price_five = 25
price_six = 35

List = store multiple values in a single variable
- Can contain any combination of data types e.g., str, float, int, bool

# List of prices
prices = [10, 20, 30, 15, 25, 35]

# List of prices using variables as values
prices = [price_one, price_two, price_three,
          price_four, price_five, price_six]

# Check the data type of a list
type(prices)

<class 'list'>

# Check the data type of a string
type("Hello")

<class 'str'>

# Print all values in the list variable
print(prices)

[10, 20, 30, 15, 25, 35]

Lists are ordered
- Can use subsetting or indexing
- Python counts values starting from zero for the first element

prices = [10, 20, 30, 15, 25, 35]

# Get the value at the first index
prices[0]

# Get the value at the fourth index
prices[3]

prices = [10, 20, 30, 15, 25, 35]

# Get the last element of a list
prices[5]

# Get the last element of a list
prices[-1]

prices = [10, 20, 30, 15, 25, 35]

# Access the second and third elements
prices[1:3]

[20, 30]

[starting_element:last_element + 1]
Add one to the last element's index because:
- Python returns everything up to but not including that index

# Access all elements from the fourth index onwards
prices[3:]

[15, 25, 35]

# Get the first three elements
prices[:3]

[10, 20, 30]

# Access every other element
prices[::2]

[10, 30, 25]

# Access every third element, starting at the second
prices[1::3]

[20, 25]

Syntax	Functionality
`a_list = [1, 2, 3, 4, 5, 6]`	Create a list variable
`a_list[0]`	Get the first element at index zero
`a_list[-1]`	Get the last element
`a_list[0:3]`	Get the first, second, and third elements
`a_list[:3]`	Get the first, second, and third elements
`a_list[2:]`	Get all elements from the third index onwards
`a_list[::2]`	Get every other element from the first index onwards

Introduction to Python for Developers